Process of transferring subjects to metal surfaces



Patented Jan. 7, I 1930 UNITED STATES HENRY L. KREBS, OF CHICAGO,ILLINOIS PROCESS OF TRAN SFERRING SUBJECTS TO METAL SURFACES No Drawing.

My invention or discovery has for its object to transfer a photographicimage, or a photographic copy of a picture, design, drawing or othersubject to a metal surface in the form of a reversed positive for thepurpose of making an etching or an engraving, or to form a foundation onwhich to build with acid proof ink or pencil.

I have discovered that a subject may be transferred directly from anyphotographic silver paper, such as a silver chloride, a silver bromide,or a silver chloride bromide paper to a zinc or copper surface of aplate, roller or other body by first bleachingthe photographic print andthen laying the print, face down, on the metal surface and moisteningthe print with a reagent that will cause such a reaction between themetal surface and the silver of the print as'to form a definite-clearimage on such surface.

Various different bleaching compounds may be employed. Good results havebeen obtained with solutions as follows: (a) a solution containing tenpercent of potassiumferri cyanide and five percent of oxalate ofpotassium. This solution may be made either stronger or more dilute. (b)a solution of twenty percent ferri cyanide. (c) a solution containingtwenty percent of fcrri cyanide and ten percent of potassium bromide.(d) a solution containing twenty percent of fcrri cyanide, five percentof potassium bromide, and five percent of potassium oxalate. (a) asolution containing ten percent of ferri cyan idc and five percent ofpotassium oxalate.

A bleaching solution that may be used .uccessfully when the transfer isto be made t) copper comprises 1.5 gram of nitrate of 1 ad, 1 gram offerri cyanide, cubic centin eter of nitric acid and 100 cubiccentimeters of water.

Still another bleaching solution may consist of 1 gram of potassiumpermanganate, 1 gram of potassium bromide, 1 cubic centimeter of a oneto twenty solution of sulphuric acid. and 200 cubic centimeters ofwater.

After the silver print has been dipped into the bleaching solution andallowed to remain there for a minute or two, it is removed from thesolution and washed. The bleaching Application filed March 29, 1928.

Serial No. 265,817.

process transforms aportion of the silver, at least, into silvercompounds whose composition depends upon the character of the bleachemployed. The print is laid, face down, upon a polished zinc or coppersurface on a plate or cylinder and is pressed into intimate contactwithsuch surface, conveniently by means of a rubber roller. The back of theprint is then moistened with a reagent to bring about a reaction betweenthe silver compounds on the print and the metal of the plate or rollerand create an image on the latter. The reagents with which I havemoistened the print lying in contact with the metal surface are dilutedaqua ammonia or strong ammonium carbonate solutions.

After about a minutefrom the time of moistening the print, the latter ispeeled from the metal surface which will be found to have thereon abrown image corresponding exactly with that in the original print. Themetal surface is then rinsed in Water and is ready for etching orengraving, or the image may be used as a foundation on which to lay acidproof inks or the like.

I am not quite certain what the chemical reactions are, but apparentlysome of the silrer is precipitated in the form of oxides, while thecopper or zinc of the plate or roller is also caused to oxidize. At anyrate, very clear images are formed on the zinc or coper. p The processis a simple one, requiring only a few minutes for its completion, sothat I am enabled very quickly to place an accurate positive image on ametal plate or roller, directly from the original subject if the latterbe a silver print, and directly from a photograph of the subject if thelatter be not a silver print.

In some cases my improved product may be put to no further use thanwould any fine photograph. On the other hand, the metal plate or rolleror other body may afterwards be employed for printing. It may beprepared for printing in any one of several ways. If the subject be onecontaining much fine detail, the artist may trace over the lines of thephotograph with an acid-proof ink, and the subject may then be etchedinto the surface of the metal in any usual way. In other cases theartist simply traces over the lines of the subject with a grease pencil,preparatory to etching or, a light coat of acld-proof varnish may beplaced over the image. After the varnish has hardened, the artist mayscratch the desired lines through the varnish, preparatory to etching.

It will be seen that where a metal plate or other body is to be used forprinting, the artist is not required .to draw the subject free hand on ametal surface or to copy it laboriously if accuracy in detail berequired my improved process providing an image in reverse that isaccurate in every detail; and the working face being left in such acondition that the subsequent operations to prepare the surface foretchin will not result in the peeling off or chipping away of parts orfragments of the image.

I claim 1. The method of forming an image on a zinc or copper surface,which consists in bleaching a silver print, laying the print on saidsurface,and applying a reagent to effect a chemical reaction between theprint and the zinc or copper.

2. The method of forming an image on a zinc or copper surface, whichconsists in bleaching a silver print, laying the print on said surface,and wetting the print with a solution of ammonia or ammonium carbonate.

3. The method of forming an image on a zinc or copper surface whichconsists in bleaching a silver print with a solution containing a ferricyanide, laying the print on said surface, and wetting the print with asolution or ammonia or ammonium carbonate.

In testimony whereof, I sign this specification.

HENRY L. KREBS.

